This information, unknown until now, has major consequences for sports performance and the prevention of metabolic pathologies
Scientists from the University of Granada (UGR) have discovered the dynamics of mitochondria when we exercise—information unknown to date, with major consequences for sports performance and the prevention of metabolic pathologies.
Mitochondria are the cellular organelles responsible for producing the energy required for eukaryotic cells, which are essential for the movement of species and for organised life.
In traditional textbooks, mitochondria are typically presented as oval, static, and unchanging organelles. “However, today we know that they function as a coordinated collective, that they are dynamic, and that they are subject to fusion or fission processes, which in turn determines their functionality and even their susceptibility to promote metabolic diseases,” explains Jesús Francisco Rodríguez Huertas, Professor at the Department of Physiology of the UGR and principal author of this work.
Cells in which fissioned mitochondria predominate lose functionality and are prone to aging and obesity. By contrast, when fusion predominates, forming long filaments, this is associated with greater functionality and the reduction of non-communicable metabolic diseases.
In this ground-breaking UGR study, the authors investigated whether mitochondrial fusion/fission processes take place in the muscle mass of athletes while training at maximum capacity.
A dual mechanism
“We have shown that mitochondria fuse into muscle within a few minutes, and they do so transversely across the myofibrils,” comments Professor Rodríguez. “This could answer one of the physiological questions that has long puzzled scientists: ‘Does oxygen really reach the centre of the muscle myofibrils during physical activity at maximum capacity?’”
The answer proved to be straightforward: the mitochondria, when fused transversely, capture the oxygen in the sarcoplasmic membrane and release adenosine triphosphate (ATP) in the centre of the myofibrils, with no need for oxygen to reach there.
The UGR scientists also demonstrated that this process is due to a dual mechanism: a molecular mechanism that activates the proteins involved in fusion, and a mechanical mechanism, because the glycogen column, in parallel to the myofibrils, squashes the mitochondria—like soap bubbles—during the contraction phase.
This mechanism is reversible, because there is a return to mitochondrial fission after three hours of rest, in which the classic oval shape depicted in the textbooks is restored.
Image caption:
Mitochondrial dynamics in muscle biopsies obtained in swimmers at rest, after 60 minutes of high-intensity exercise and subsequently three hours of recovery. Mitochondria appear surrounded by yellow.
The proposed mitochondrial fission mechanism, crushing the glycogen column during the contraction of myofibrils.
The UGR research team that conducted the study.
Bibliography:
Jesús R. Huertas, Francisco Javier Ruiz-Ojeda, Julio Plaza-Díaz, Nikolai B. Nordsborg, Jesús Martín-Albo, Ascension Rueda-Robles, and Rafael A. Casuso, ‘Human muscular mitochondrial fusion in athletes during exercise’, The FASEB Journal 33(11), November 2019. https://doi.org/10.1096/fj.2019003 65RR.
Media enquiries:
Jesús Francisco Rodríguez Huertas, Professor, Department of Physiology, University of Granada. Institute of Food Nutrition and Technology (INYTA). Biomedical Research Centre (CIBM).
Tel.: 958 241000 ext.: 20319
Email: jhuertas@ugr.es
